In typical heat exchangers, when a plate-like fin and a flat heat transmission pipe are brazed together, a short-axial-length portion of a flat heat transmission pipe 2 is located downward in the direction of gravity. Thus, a brazing material 4 is fixed and is sufficiently distributed so that the heat exchanger can exhibit high heat exchange performance (see, for example, Patent Literature 1).
A heat exchanger fin in which a reflared portion that bends toward a direction opposite to the side in contact with a heat transmission pipe is formed in at least part of a tip of a fin collar and the distance between the upper surface of the reflared portion and the fin base surface is equal to a pitch between stacked fins has also been proposed (see, for example, Patent Literature 2).